The detailed mechanisms of serine hydroxymethylase and cis, cis-muconate lactonizing enzyme will be determined by pre-steady state, steady state, and relaxation kinetic analyses in the presence of various concentrations of substrates, products, and inhibitors. From the pH dependencies of the elementary steps in the kinetic sequences, isolation of possible covalent enzyme-substrate moiety intermediates or enzyme-suicide substrate irreversible complexes, isotopic exchange reactions and kinetic isotope effects the detailed mechanisms of the enzymes will be elucidated. Structure-function correlations involving active site residues will be performed. These correlations will be compared with data obtained in relevant model system studies in order to further elucidate the contributions to catalysis in the enzyme catalyzed sequences.